Gun control advocates in San Diego are backing a national campaign this weekend to use a simple question to help parents find out more about where kids are playing.

On Asking Saves Kids Day on Sunday, advocates want parents to pose this question to their kids’ friends: Do you have an unlocked gun in your house?

According to the Asking Saves Kids, or ASK, website, one in three homes with children in the United States has guns in it, and 80 percent of unintentional deaths of kids under the age of 15 occur in the home.